[amsat-bb] When exactly is a non-conductive mast necessary?

[Jeff Moore]

I'm sorry - that's way too general of an answer to be accurate.   Physics
says it's impossible to stick a significant piece of metal in the near
field of an antenna and NOT have an effect!   The only valid question is
HOW MUCH OF AN EFFECT THERE WILL BE!

7   3
Jeff Moore  --  KE7ACY
CN94


On Mon, Dec 30, 2019 at 2:32 PM Gary via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> The short answer is almost never. Here is a link to an AMSAT Symposium
> paper form antenna guru Kent Britain, wa5vjb (inventor of the famous cheap
> yagis). He actually measured the effects.
> http://www.kk0sd.net/metalboom/metalboom.htm
>
>
> 73,
> Joe kk0sd
>
>
> -----Original Message-----
> From: AMSAT-BB <amsat-bb-bounces at amsat.org> On Behalf Of Cathryn Mataga
> via AMSAT-BB
> Sent: Monday, December 30, 2019 3:27 PM
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] When exactly is a non-conductive mast necessary?
>
> I'm trying to understand, under what circumstances is a non-conductive
> mast necessary at VHF/UHF frequencies. Thinking of the following installs.
>
> 1.  Circular polarized antenna mounted to the mast at the center of the
> boom.    This is clear, see this advice all the time, fiberglass mast.
>
> 2. Same antenna but mounted at the rear end of the boom.
>
> 3.  Vertical Yagi, elements parallel to a vertical mast, mounted at the
> center of the boom. I guess, non-conductive wold be required here.
>
> 4.  Same antenna but rear mounted.
>
> 5.  Horizontal Yagi, elements perpendicular to a vertical mast, mounted at
> the center of the boom.  I think this is pretty normal install, so a
> conductive mast would be okay?
>
> 6. Same antenna but mounted at the rear of the boom.
>
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> expressed
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